The present application relates to a semiconductor structure and a method of forming the same. More particularly, the present application relates to a semiconductor-on-insulator (SOI) lateral bipolar transistor having a completely shielded intrinsic base semiconductor material portion and a method of forming the same.
Bipolar junction transistors are typically found in demanding types of analog circuits, especially analog circuits used in high-frequency applications. For example, bipolar junction transistors can be found in radio frequency integrated circuits (RFICs) used in wireless communication systems, as well as integrated circuits requiring high power efficiency, such as power amplifiers in cellular telephones, and other types of high speed integrated circuits. Bipolar junction transistors may be combined with complementary metal-oxide-semiconductor (CMOS) field effect transistors in bipolar complementary metal-oxide-semiconductor (BiCMOS) integrated circuits, which take advantage of the favorable characteristics of both transistor types.
Conventional bipolar junction transistors such as vertical bipolar transistors, include three semiconductor regions, namely the emitter, base, and collector regions. Generally, a bipolar junction transistor includes a pair of p-n junctions, namely an emitter-base junction and a collector-base junction. A heterojunction bipolar transistor (HBT) is a variety of bipolar junction transistor that employs at least two semiconductor materials with unequal band gaps for the emitter/collector and base regions, creating a heterojunction.
With the advent of semiconductor-on-insulator (SOI) technology, innovative thin-base lateral bipolar transistors have been developed. In prior art SOI lateral bipolar transistors, charge build-up may occur in the buried oxide layer of the SOI substrate that is located directly beneath the lightly doped intrinsic base. Charge build-up within the buried oxide layer of such a structure can change the device characteristic. For example, charge build-up in the buried oxide layer of SOI lateral bipolar transistors can change the device collector current. Hence, there is a need for providing SOI lateral bipolar transistors in which charge build-up within the buried oxide layer of such a structure is circumvented.